With their exceptionally high energy density, lithium-metal batteries could dramatically increase electric vehicle driving ranges and speed up charging.
However, there’s a big hurdle for creating practical rechargeable lithium-metal batteries: the formation of dendrites. Dendrites, or tiny metallic “branches,” develop over time in lithium-metal anodes and can trigger short circuits, posing severe safety risks and limiting battery lifespan.
Now Weiyu Li, an assistant professor of mechanical engineering at the University of Wisconsin-Madison, and her PhD student Hongtao Sun have gained new insights into how dendrites form and grow in lithium-metal batteries. Based on findings from their high-resolution simulations, the researchers developed generalizable design rules for engineering stable lithium-metal anodes.
“Our design rules can increase efficiency and save manufacturers from a lot of trial and error in creating better lithium-metal anodes, because we’re providing them with insights into the key surface design parameters that control stability,” Li says.
The researchers detailed their findings in a paper published in the May 2026 issue of the journal Nano Energy.
In lithium-metal batteries, it’s important for the interface between the lithium-metal anode and the electrolyte to be stable. “When that interface is destabilized, dendrites will grow very fast and they can penetrate the separator, causing the battery to short out completely,” Sun says. “That’s why we’re investigating how to stabilize this interface and ultimately suppress dendrite formation, which is essential for enabling practical, high-energy-density lithium-metal batteries.”
Li and Sun examined how nanoscale surface roughness and intrinsic defects on the lithium-metal anode jointly govern dendrite growth in lithium-metal batteries. Using high-resolution nonlinear phase-field simulations, they identified roughness wavelength as a key control parameter for stabilizing the interface. Traditional linear theories can predict the early onset of instability, but Li and Sun’s simulations capture the later nonlinear growth stage, where surface roughness and defects interact in more complex ways.
This finding is important because surface roughness can potentially be tuned during anode fabrication. Rather than aiming only for perfectly smooth surfaces, the researchers found that carefully designed nanoscale roughness can help suppress dendrite growth.
To dial in the ideal surface roughness, the researchers investigated nanoscale structures shaped like a wave that consists of tiny peaks and valleys. Their simulations showed that stability depends on the coupled interaction between roughness wavelength, roughness amplitude and defect characteristics. Short-wavelength roughness can stabilize the interface, even when defects are present, while long-wavelength roughness can become destabilizing if its amplitude is too large. “From our simulations, we can provide manufacturers with specific roughness wavelengths and amplitudes as key control parameters to inform their design strategy,” Li says. “Our results demonstrate that nanoscale roughening, beyond simply reducing defects, is an effective and tunable strategy for stabilizing lithium-metal interfaces.”
The researchers also found that defects play a more nuanced role than previously understood. While large or dense defects still promote dendrite growth, a moderate number of small defects can, under certain surface roughness conditions, interrupt the growth of long-wavelength instabilities and reduce dendrite extension.
Weiyu Li is the Alfred Fritz assistant professor of mechanical engineering. Hongtao Sun is a first-year PhD student in mechanical engineering in Li’s Energy and Sustainability Solutions Lab.
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